Hig concentration of ground-level ozone is undesirable because it initiates photochemical smog formation, and is also detrimental to human health. Continuous monitoring of ozone is essential to measure its variability, its transport across regional boundaries, and the dynamic sources and sinks that control its production. We propose to develop a novel compact differential absorption lidar (DIAL) to continuously measure ozone concentration profiles with sufficient sensitivity (10ppb) and accuracy (10%), for 10km range with 500m resolution, for averaging under one hour. A high repetition rate (1kHz), tunable (280-295nm), 0.5mJ/pulse Ce:LiSAF laser, which is pumped by the fourth harmonic (266nm) diode-pumped Nd:YAG laser, will provide both on-and off-line pulses. The optimum on-and off-line laser wavelengths are chosen between 286 and 292nm. Atmospheric back scattered signals is collected by a 35cm aperture telescope that can be scanned to allow horizontal, vertical or slant path measurements. This ruggedized lidar will be housed in a small van for mobility, and provided with autonomous operation capability. In Phase I a comprehensivedesign of the ozone lidar will be performed together with a feasibility demonstration using a bread-board lidar. In Phase II, the prototype mobile ozone lidar will be built and used for ozone transport measurements.